A radar sensor which is fastened with screws to the outside of a vehicle using a support is described in German Patent Application No. 197 39 298, for example. This radar sensor may, for example, be a module of a vehicle safety system, in which information about the distance and/or relative speed of the vehicle to other vehicles and to the road surroundings is processed continuously. In this case, it is necessary that the radar sensor be aligned very exactly on the longitudinal axis of the vehicle, i.e., in particular that the focusing of the antenna unit is ensured even over relatively long periods of time.
In the conventional arrangement, the antenna component, which may be constructed as a polyrod from a special plastic for antennas, is rigidly attached to a structure using standard fasteners, no height tolerance compensation in the signal direction being provided. Since the components are subjected to both manufacturing tolerances and to differing thermal expansions, it may occur in this case that the polyrod disengages via the antenna patch to which it has contact in the radar sensor circuit or it is pressed so strongly against the antenna patch that it deforms elastically. Both mechanisms may reduce the antenna focusing function or cause it to fail completely, which negatively affects the signal transmission of the radar sensor. Furthermore, the polyrod may also strongly deform due to its low intrinsic rigidity which may also result in a reduction or failure of the focusing function.